Samuel André Rolland

• PhD
• Senior Lecturer at Swansea University

Purpose – This study aims to analyse the non-linear losses of a porous media (stack) composed by parallel plates and inserted in a resonator tube in oscillatory flows by proposing numerical correlations between pressure gradient and velocity. Design/methodology/approach – The numerical correlations origin from computational fluid dynamics simulati...

Year-in-industry schemes provide new or enhanced skills beyond the academic environment, a context for consolidation for the academic skills and a maturity in the approach to subsequent studies. The present work aims to quantify the impact of the year in industry placement scheme on academic outcomes for engineering students according to whether or...

Purpose The purpose of this paper is to devise a tool based on computational fluid dynamics (CFD) and machine learning (ML), for the assessment of potential airborne microbial transmission in enclosed spaces. A gated recurrent units neural network (GRU-NN) is presented to learn and predict the behaviour of droplets expelled through breaths via part...

Purpose A novel modelling approach is proposed to study ozone distribution and destruction in indoor spaces. The level of ozone gas concentration in the air, confined within an indoor space during an ozone-based disinfection process, is analysed. The purpose of this work is to investigate how ozone is distributed in time within an enclosed space....

OBJECTIVES The aim of this work is to investigate the hydraulic and blood damage performance of Ventricular Assist Devices (VAD) under pulsatile conditions using Computational Fluid Dynamics. METHODS The fluid domains of CentriMag, HeartMate II (HM2) and HVAD were extracted from the CAD files, and numerical simulations were performed using ANSYS C...

Cardiopulmonary bypass procedures are one of the most common operations and blood oxygenators are the centre piece for the heart-lung machines. Blood oxygenators have been tested as entire devices but intricate details on the flow field inside the oxygenators remain unknown. In this study, a novel method is presented to analyse the flow field insid...

Considering the use of commercial-off-the-shelf(COTS) devices in industry, a case study has been undertaken implementing the goal driven optimisation of a venturi-type pre-mixer. This COTS device is used to supply the correct ratio of a specific fuel and oxidiser to a pre-mix burner. Providing the correct quantity of excess air results in a reducti...

This paper numerically investigates non-Newtonian blood flow with oxygen and carbon dioxide transport across and along an array of uniformly square and staggered arranged fibres at various porosity (e) levels, focussing on a low Reynolds number regime (Re < 10). The objective is to establish suitable mass transfer correlations, expressed in the for...

The emergence of Additive Layer Manufacturing (ALM) is an exciting development in powder metallurgy, which requires powder of consistently high quality. Gas atomisation is a specialised processing route for the production of fine, spherical powders. However, fully understanding and exerting a high level of control over this process is a challenge f...

Objectives The current work introduces particle tracks recirculation analysis to better represent laboratory haemolysis experiments and to improve the CFD haemolysis predictions in VADs. Method Three approaches were implemented to match simulation residence time to experiment time. The first is ‘Scaled Single Pass’ (SSP) and it is a linear scaling...

This paper reviews and further develops pore-scale computational flow modelling techniques used for creeping flow through orthotropic fibre-bundles used in blood oxygenators. Porous model significantly reduce geometrical complexity by taking a homogenisation approach to model the fibre bundles. This significantly simplifies meshing and can avoid la...

Powder metallurgy (PM) refers to a range of engineering techniques whereby net shape or near-net shape bodies are produced through the aggregation of a powder substrate. Specifically, the emergence of Additive Layer Manufacturing (ALM) is an exciting development in this field. However, the quality of any product produced by ALM is highly dependent...

The approach and results of a parametric aerodynamic optimisation study is presented to develop the blade design for a novel implementation of a vertical axis wind turbine. It was applied to optimise the two-dimensional cross-sectional geometry of the blades comprising the turbine. Unsteady viscous computational fluid dynamic simulations were used...

As advances in numerical modelling techniques support the increased confidence in predictions from computer simulations, the need remains to have experimental verification built into the design process. This paper outlines the experimental investigation carried out on a shielded vertical axis turbine in a marine environment. The experiments consist...

Powder Metallurgy (PM) refers to a range of engineering techniques whereby net shape or near-net shape bodies are produced through the aggregation of a powder substrate. Gas atomisation is a very efficient processing route in the PM field for the production of fine powders directly from a molten metal melt. The close-coupled gas atomisation process...

In this current work, an alternative efficient framework to evaluate the behaviour of flow in random fibrous porous media of oxygenators is proposed. This methodology aims improve the iterative nature of oxygenator design without the effort of remeshing. The geometry of the oxygenator is extracted from a micro-CT image and their fibre coordinates a...

Purpose: The development of a VAD is a compromise between optimal pressure-flow/efficiency and minimal blood damage. A set of tools were developed to provide flow-specific measurable quantities from a CFD flow domain that predict the likely blood damage caused by the flow as a result of exposure to high shear stresses (τ) and residence times (RT)....

Aim: Develop and validate a computational fluid dynamics (CFD) model of the Calon MiniVAD, and use it to produce an impeller design with a flat pressure–flow (HQ) curve, maximum efficiency (η) and minimal shear stress. Methods: A set of impellers were designed and built with identical blade shapes, but with differing heights. Flow domains were ext...

Ventricular assist devices (VADs) are used for circulatory support in patients with heart failure. Computational fluid dynamics (CFD) have been used extensively to model the performance of these devices and to improve their design characteristics. Additionally, CFD have been employed to assess the damage to blood (haemolysis) as a result of exposur...

Blood oxygenators are fundamental to open heart surgery and to accelerate pulmonary recovery for patients with severely impaired lung function. For the last decade, Extra Corporeal Membrane Oxygenator (ECMO) devices based on micro-porous Hollow Fibre Membranes (HFM) have dominated the scene. Here we present a methodology to reconstruct the three-di...

Blood oxygenator is a medical device primarily applied in surgical procedures such as open-heart surgery and could also be used as a long term respiratory support for patients suffering from respiratory failure. The aim of this study was to get a better understanding of the non-Newtonian flow behaviour in hollow fibre oxygenators through Computatio...

An investigation has been undertaken into the mixing mechanisms involved in a closed tank stirred vessel utilising a wide paddle agitator, for fluids in the viscosity range of 1 to 5.5 mPa s. In particular, the effect of fill depth on the mixing time has been considered, as this has a direct impact on the usability of the mixing process equipment f...

A goal driven optimisation process has been undertaken for a Venturi-type premixer. Premixers are used to supply the correct mixture of fuel and oxidiser to a premix burner; providing the correct quantity of excess air results in a reduction of nitrogen oxides (NOx). A computational fluid dynamic (CFD) simulation has been undertaken using FLUENT 14...

Driven by the need to verify a CFD model of a novel vertical axis wind turbine (VAWT) device, a 1.6 m diameter prototype was designed, built to a high specification and tolerance and then tested in the industry standard MIRA wind tunnel over the full wind range that might be expected in an urban environment. Although the original intention was simp...

Computational fluid dynamics (CFD) simulation tools are developed to analyse the aerodynamic performance of a novel design vertical axis wind turbine (VAWT) and compared against careful data from a 1.6 m diameter device in a wind tunnel. The study investigates the extent to which a CFD model employing the simplest turbulence representation can prov...

Optimization techniques have been used extensively over the last decades to assist in the design of steel structures. This paper describes the integrated use of a number of these techniques in the costing and design of a large-scale housing for a Vertical Axis Wind Turbine (VAWT) satisfying British Standards. The problem is complex with seven diffe...

A modelling approach is proposed to study ozone distribution and destruction in indoor spaces. The level of ozone gas concentration in the air, confined within an indoor space during an ozone-based disinfection process, was modelled. The emission and removal of ozone from the air volume were carried out using a generator located in the middle of th...

Numerical simulations of manufacturing processes rely on material characterisation. This highlights the need for a close combination of experimental and numerical work to model cold die powder compaction. Based on a previous experimental work by the authors, this document shows how the data collected can be used to formulate a constitutive model re...

The powder forming industry looks to produce parts of increasing geometrical complexity as it is seen as a very efficient production process. This offers new challenges as three-dimensional states of stress are induced. In particular, granular and porous materials respond very differently to tensile and compressive stresses. Since experiments condu...

Cold die powder compaction can be a challenging manufacturing route for complex components. Setting the filling and pressing tools is a difficult and time consuming operation. Numerical methods can assist process engineers; however, the result can only reflect the reality if the material characteristics are well established mathematically for the s...

This article addresses the occurrence of crack-related failure within the powder compaction cycle. Both tensile and shear cracks are considered together with the challenges associated with their detection. Experimental data are presented from the compaction of multi-level parts pressed from DistaloyAE powder to green densities between 6 and 7 g/cm3...

The challenges of parallelisation for CFD have long been addressed. The strategy of load balancing through mesh partitioning is now well established and there are many tools around to support this strategy. However, although these strategies are well established and work really well in some contexts, scalability is not guaranteed for all applicatio...

Powder compaction modelling has been shown to be accurate to simulate the pressing of simple components, in programmes such as the EU funded networks Modnet and Dienet. Difficulties arise when complex shapes and heterogeneous compaction ratios are encountered in the pressed parts. The present work looks to propose a numerically simple constitutive...

This chapter gives examples of the successful use of compaction modelling (CM) by industry. The examples complement those for the parmaceutical industry in Chapter 14 and have been selected to illustrate the use of CM in solving common industry problems.

An integrated approach has been taken to the prediction and non-destructive detection of cracking in green compacts. This includes assessment of a number of simple tests that indicate tendency to initiation of cracking in green compacts, enhancement of an existing finite element model for compaction to indicate risk of cracking during compaction an...